title: Interactions between white matter asymmetry and language during neurodevelopment.
abstract: The human brain is asymmetric in gross structure as well as functional organization. However, the developmental basis and trajectory of this asymmetry is unclear, and its relationship(s) to functional and cognitive development, especially language, remain to be fully elucidated. During infancy and early childhood, in concert with cortical gray matter growth, underlying axonal bundles become progressively myelinated. This myelination is critical for efficient and coherent interneuronal communication and, as revealed in animal studies, the degree of myelination changes in response to environment and neuronal activity. Using a novel quantitative magnetic resonance imaging method to investigate myelin content in vivo in human infants and young children, we investigated gross asymmetry of myelin in a large cohort of 108 typically developing children between 1 and 6 years of age, hypothesizing that asymmetry would predict language abilities in this cohort. While asymmetry of myelin content was evident in multiple cortical and subcortical regions, language ability was predicted only by leftward asymmetry of caudate and frontal cortex myelin content and rightward asymmetry in the extreme capsule. Importantly, the influence of this asymmetry was found to change with age, suggesting an age-specific influence of structure and myelin on language function. The relationship between language ability and asymmetry of myelin stabilized at ∼4 years, indicating anatomical evidence for a critical time during development before which environmental influence on cognition may be greatest.
authors.affiliation: Advanced Baby Imaging Laboratory, School of Engineering, Brown University, Providence, Rhode Island 02912, Department of Neuroimaging, King's College London, Institute of Psychiatry, London WC2R 2 LS, United Kingdom, and Alpert Medical School of Brown University, Providence, Rhode Island 02912.
authors.forename: Jonathan
authors.initials: J
authors.lastname: O'Muircheartaigh
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Dean
authors.forename: Holly
authors.initials: H
authors.lastname: Dirks
authors.forename: Nicole
authors.initials: N
authors.lastname: Waskiewicz
authors.forename: Katie
authors.initials: K
authors.lastname: Lehman
authors.forename: Beth A
authors.initials: BA
authors.lastname: Jerskey
authors.forename: Sean C L
authors.initials: SC
authors.lastname: Deoni
mesh_terms: D001921:Brain / Q000254:growth & development*; D002648:Child; D002675:Child, Preschool; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007223:Infant; D007804:Language Development; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000502:physiology*